Since the terror event happened on Sep. 11, 2001 in US, anti-terror has become a common topic all over the world. Also, terror events have happened in U.S.A., Russia, U.K., Egypt, Spain, Indonesia, India and the like, and U.S.A. even provoked two wars for this reason. Terrorists often start a terror attack with “human bombs”, which severely threatens the security of common people and the social stability.
Generally, security doors in the market for inspecting a person, however, can only detect magnetic metals, and can not detect non-magnetic metals. Therefore, they can not detect explosives and narcotic drugs, which is a serious security loop-hole.
It is possible to detect suspicious particles of the narcotic drugs, explosives and the like carried by the person with the development of the narcotic drug/explosive detecting (IMS) technique. Recently, a great many of efforts have been made on a door-type person detecting technique using the IMS technique, and a number of patent applications, such as EP1286151A1, U.S. Pat. No. 5,915,268A1, U.S. Pat. No. 6,073,499A1 and US2001049926A1 etc. have been filed.
In those patent applications, a plurality of door structures is provided to facilitate collecting airflows; a concentration concept is employed (for example, in U.S. Pat. No. 6,073,499A1) to improve collection efficiency. And in order to blow down the suspicious particles carried on the person's clothes, various methods are used, such as a continuous airflow is blown towards the person being inspected, as described in US2001049926A1; and a jet head for air-spraying pressurized air is added later to blow the clothes, as well as the setting of the airflow and the direction of the jet head, for example, upward or downward, as described in EP1286151A1, U.S. Pat. No. 5,915,268A1, and U.S. Pat. No. 6,073,499A1.
In order to detect special nucleus substances and radioactive substances, Chinese patent CN02289581.4 proposes a door-type γ radioactivity security inspecting device in which NaI (TI) scintillating medium for measuring the γ radioactivity are shielded directionally so that only the γ radioactivity in a spatial angle range at one side of the scintillating medium can be detected; and a plurality of γ probes are arranged in doorposts at two sides of a doorframe to improve efficiency of detecting the radioactive substances. US2006/028494A1 also provides a radioactive security inspection door in which a plurality of detectors and a collimator array are applied to achieve the function of detecting the γ and n simultaneously.
In the aspect of metal detecting, Chinese patent CN1834690 provides a pass-through metal detecting system, in which a double transmitting and a double receiving antenna and corresponding circuits and software are used to improve the defect that the magnetic field is not distributed uniformly, and thus the ability of metals detection is improved. Chinese patent CN1802675A (WO2004/097456) provides a metal detector with a portable structure, and the metal detector may operate for a long time by means of battery or an AC power supply by setting a heavy load cycle working mode and an impulse working mode.
However, for various reasons, a detecting device, which can detect the narcotic drugs/the explosives, the radioactive substances and the dangerous metal articles at the same time, can not be founded in the market.